x402 Precheck MCP Server

About x402 Precheck

Pre-payment check for x402 (HTTP 402) payments. Give an endpoint URL (probed unpaid, never paid) or paste a 402 challenge; get pass/warn/fail checks on x402 version, scheme, CAIP-2 network and testnet flag, canonical USDC asset, amount sanity and your max price, payTo format / EIP-55 checksum / zero address / expected recipient, EIP-712 domain, payment window, facilitator reachability and scheme+network support, PayAI Bazaar listing match. Verdict: looks_ok / review / do_not_pay. 0.002 USDC per check on Base via x402; free trial 1024 checks per IP per day. No signup. Built and operated with AI assistance. One MCP tool: x402_precheck (args: url or challenge, optional maxPriceUsd, expectPayTo, expectNetwork, facilitator). No auth; paid per call via the x402 MCP transport after the free trial.

x402 Precheck tools (1)

Read from the live server on Nov 13, 2026. These are the tools your AI assistant can call once connected.

x402_precheck

Check an x402 payment challenge BEFORE your agent pays (0.002 USDC per check via x402; free trial 1024 checks/IP/UTC day). Give an endpoint URL (fetched unpaid, never paid) or paste a 402 challenge. Validates x402 version, scheme, network (

How to connect x402 Precheck to Claude, Cursor or VS Code

x402 Precheck runs as a hosted remote MCP server at https://x402-precheck.w0arvg81zlgf.workers.dev/mcp. Add that URL to your MCP client's config (Claude Code, Cursor, Windsurf or VS Code) and the tools appear immediately, no install required.

{
  "mcpServers": {
    "x402-precheck": {
      "url": "https://x402-precheck.w0arvg81zlgf.workers.dev/mcp"
    }
  }
}

Claude Code: claude mcp add --transport http x402-precheck https://x402-precheck.w0arvg81zlgf.workers.dev/mcp. VS Code's .vscode/mcp.json uses a servers key instead of mcpServers (see how). Servers that require OAuth or an API key will prompt on first use.